Windows, doors or other openings in buildings form parts of the building structure which can fail during extreme temperature conditions and which thereafter allow entry into the building of flames and embers, and of oxygen which fuel the flames and embers. Once a fire is established within a building, it is difficult to save the building from complete destruction. Accordingly, it is recognised that protection of windows, doors and other openings in a building is important in order to protect buildings against destruction by fire.
Windows can be protected by shutters which typically are positioned to form a cover over the external side of the window. Shutters exist already to close over a window and certain shutters have been developed for protection of windows in bushfire conditions. However, shutters of which the applicant is aware typically are aluminium roller shutters and a disadvantage with these shutters is that the melting temperature of aluminium can be lower than the temperature to which the shutter is exposed during a bushfire, so that the aluminium shutter could melt in such extreme temperature conditions. For that reason, recent amendments in Australia to building standards require shutters used for protection in bushfire conditions to continue to operate in a protective manner in temperatures exceeding the melting point of aluminium, i.e. in temperatures beyond 700° C.
Some existing shutters have been constructed in steel, which has a higher melting temperature than aluminium and so does not suffer the same drawbacks as aluminium. However, these shutters do not prevent transmission of radiant heat from the external or fire side of the shutter to the internal or non-fireside, and because of that radiant heat transmission, it is often the case that the window frame or the glass of the window fails even though the shutter is in a position covering the window. These forms of shutters also have sealing issues and therefore can leave gaps between the shutter and the surrounds of the window and this allows ingress of embers and oxygen.
There are also flame and smoke control ‘curtain’ type products, typically used in indoor environments to prevent the spread of fire from one area of a building to another. These products however have limited benefit when applied externally over windows or doors, as they can be deflected or shifted by wind, or if hit by flying embers and other debris for example, causing the glass of the window to break or allowing ember and heat access to the frame of the window or door. Such curtain type products are also not primarily designed for deflecting the heat, so that they can allow the cavity between the curtain and the window or door to get excessively hot and thus cause the window glass or window or door frame to fail.
Some curtain fabrics exist that do have fire retardant or heat reflective properties, but these fabrics are not necessarily capable of long term external use. In addition, they can also present difficulties for mounting, so that prohibitively expensive and difficult mounting arrangements are required.
Accordingly, applicant is not aware of a shutter which operates successfully under extreme temperature conditions as can occur during some extreme bushfire events. The applicant has therefore developed a new and unique shutter which aims to overcome or at least alleviate some of the disadvantages with shutters of the prior art.